全文获取类型
收费全文 | 169篇 |
免费 | 3篇 |
国内免费 | 19篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 20篇 |
地球物理 | 39篇 |
地质学 | 69篇 |
海洋学 | 17篇 |
天文学 | 29篇 |
综合类 | 1篇 |
自然地理 | 9篇 |
出版年
2023年 | 2篇 |
2021年 | 7篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 10篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 16篇 |
2009年 | 10篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 9篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有191条查询结果,搜索用时 15 毫秒
1.
2.
David Savage Josep M. SolerKohei Yamaguchi Colin WalkerAkira Honda Manabu InagakiClaire Watson James WilsonSteven Benbow Irina GausJoerg Rueedi 《Applied Geochemistry》2011,26(7):1138-1152
The use of cement and concrete as fracture grouting or as tunnel seals in a geological disposal facility for radioactive wastes creates potential issues concerning chemical reactivity. From a long-term safety perspective, it is desirable to be able model these interactions and changes quantitatively. The ‘Long-term Cement Studies’ (LCS) project was formulated with an emphasis on in situ field experiments with more realistic boundary conditions and longer time scales compared with former experiments. As part of the project programme, a modelling inter-comparison has been conducted, involving the modelling of two experiments describing cement hydration on one hand and cement-rock reaction on the other, with teams representing the NDA (UK), Posiva (Finland), and JAEA (Japan).This modelling exercise showed that the dominant reaction pathways in the two experiments are fairly well understood and are consistent between the different modelling teams, although significant differences existed amongst the precise parameterisation (e.g. reactive surface areas, dependences of rate upon pH, types of secondary minerals), and in some instances, processes (e.g. partition of alkali elements between solids and liquid during cement hydration; kinetic models of cement hydration). It was not conclusive if certain processes such as surface complexation (preferred by some modellers, but not by others) played a role in the cement-rock experiment or not. These processes appear to be more relevant at early times in the experiment and the evolution at longer timescales was not affected. The observed permeability profile with time could not be matched. The fact that no secondary minerals could be observed and that the precipitated mass calculated during the simulations is minor might suggest that the permeability reduction does not have a chemical origin, although a small amount of precipitates at pore throats could have a large impact on permeability.The modelling exercises showed that there is an interest in keeping the numerical models as simple as possible and trying to obtain a reasonable fit with a minimum of processes, minerals and parameters. However, up-scaling processes and model parameterisation to the timescales appropriate to repository safety assessment are of considerable concern. Future modelling exercises of this type should focus on a suitable natural or industrial analogue that might aid assessing mineral-fluid reactions at these longer timescales. 相似文献
3.
Erling K. Stenevik Webjrn Melle Eilif Gaard Astthor Gislason Cecilie T.. Broms Irina Prokopchuk Bjrnar Ellertsen 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2672
Egg production of Calanus finmarchicus was studied during joint basin-scale surveys in April–June 2003 in the Norwegian Sea. Surveys covered the whole Norwegian Sea and were conducted from Norwegian, Icelandic and Faroese research vessels. Stations were classified as being in pre-bloom, bloom or post-bloom phase according to levels of chlorophyll a and nitrate. Individual egg production rates and population egg production rates were calculated and compared between areas. Both individual egg production rates (eggs female−1 day−1) and population egg production rates (eggs m−2 day−1) were significantly higher in bloom areas compared with pre-bloom and post-bloom areas. However, when integrated over an estimated duration of the three phases, the time-integrated egg production (eggs m−2) in most years was highest in the pre-bloom phase, and this was explained by the longer duration of this phase compared with the two other phases. 相似文献
4.
Victor G. Kornilov Vladimir M. Lipunov Evgeny S. Gorbovskoy Aleksander A. Belinski Dmitry A. Kuvshinov Natalia V. Tyurina Nikolai I. Shatsky Anatoly V. Sankovich Aleksander V. Krylov Pavel V. Balanutsa Vadim V. Chazov Artem S. Kuznetsov Dmitry S. Zimnuhov Victor A. Senik Andrey G. Tlatov Aleksander V. Parkhomenko Denis V. Dormidontov Vadim V. Krushinsky Ivan S. Zalozhnyh Aleksander A. Popov Sergey A. Yazev Nikolai M. Budnev Kirill I. Ivanov Evgeny N. Konstantinov Oleg A. Gress Oleg V. Chvalaev Vladimir V. Yurkov Yury P. Sergienko Irina P. Kudelina 《Experimental Astronomy》2012,33(1):173-196
Presented paper describes the basic principles and features of the implementation of a robotic network of optical telescopes MASTER, designed to study the prompt (simultaneous with gamma radiation) optical emission of gamma-ray bursts and to perform the sky survey to detect unknown objects and transient phenomena. With joint efforts of Sternberg astronomical institute, High altitude astronomical station of the Pulkovo observatory, Ural state university, Irkutsk state university, Blagoveshchensk pedagogical university, the robotic telescopes MASTER?II near Kislovodsk, Yekaterinburg, Irkutsk and Blagoveshchensk were installed and tested. The network spread over the longitudes is greater than 6?h. A further expansion of the network is considered. 相似文献
5.
Irina?ZhukovaEmail author Hugh?O’Neill Ian?H.?Campbell 《Contributions to Mineralogy and Petrology》2017,172(7):53
Diffusion of Al in synthetic forsterite was studied at atmospheric pressure from 1100 to 1500 °C in air along [100] with activities of SiO2, MgO and Al2O3 (aSiO2, aMgO and aAl2O3) buffered. At low aSiO2, the buffer was forsterite + spinel + periclase (fo + sp + per) at all temperatures, while at high aSiO2 and subsolidus conditions a variety of three-phase assemblages containing forsterite and two other phases from spinel, cordierite, protoenstatite or sapphirine were used at 1100–1350 °C. Experiments at high aSiO2 and 1400 °C used forsterite + protoenstatite + melt (fo + en + melt), and at 1500 °C, fo + melt. The resulting diffusion profiles were analysed by LA–ICP–MS in scanning mode. Diffusion profiles in the high aSiO2 experiments were generally several hundred microns in length, but diffusion at low aSiO2 was three orders of magnitude slower than in high aSiO2 experiments carried out at the same temperature, producing short profiles only a few microns in length and close to the spatial resolution of the analytical method. Interface concentrations of Al in the forsterite, obtained by extrapolating the diffusion profiles to the crystal/buffer interface, were only a fraction of those expected at equilibrium, and varied among the differing buffer assemblages according to (aAl2O3)1/2 and (aSiO2)3/4, pointing to the substitution of Al in forsterite by an octahedral-site, vacancy-coupled (OSVC) component with the stoichiometry Al 4/3 3+ vac2/3SiO4, whereas the main substitution expected from previous equilibrium studies would be the coupled substitution of 2 Al for Mg + Si, giving the stoichiometry MgAl2O4. It is proposed that this latter substitution is not seen on the length scales of the present experiments because it requires replacement of Si by Al on tetrahedral sites, and is accordingly rate-limited by the slow diffusivity of Si. Instead, diffusion of Al by the OSVC mechanism is relatively fast, and at high aSiO2, even faster than Fe–Mg interdiffusion. 相似文献
6.
Climate Dynamics - We analyze for the first time all 16 Coupled Model Intercomparison Project Phase 5 models with explicit marine ecological modules to identify the common mechanisms involved in... 相似文献
7.
Andrey M. Korjenkov J. Ramon Arrowsmith Christopher Crosby Ernes Mamyrov Lyubov A. Orlova Irina E. Povolotskaya Kubatbek Tabaldiev 《Journal of Seismology》2006,10(4):431-442
A paleoseismological study of the medieval Kamenka fortress in the northern part of the Issyk-Kul Lake depression, northern Tien Shan in Kyrgyzstan, revealed an oblique slip thrust fault scarp offsetting the fortification walls. This 700 m long scarp is not related to the 1911 Kebin Earthquake (Ms 8.2) fault scarps which are widespread in the region. As analysis of stratigraphy in a paleoseismic trench and archaeological evidence reveal, it can be assigned to a major twelfth century a.d. earthquake which produced up to 4 m of oblique slip thrusting antithetic to that of the nearby dominant faults. The inferred surface rupturing earthquake apparently caused the fortress destruction and was likely the primary reason for its abandonment, not the Mongolian–Tatar invasions as previously thought. 相似文献
8.
9.
Sophie GODIN-BEEKMANN Irina PETROPAVLOSKIKH Stefan REIS Paul NEWMAN Wolfgang STEINBRECHT Markus REX Michelle L. SANTEE Richard S. ECKMAN Xiangdong ZHENG Matthew B. TULLY David S. STEVENSON Paul YOUNG John PYLE Mark WEBER Johanna TAMMINEN Gina MILLS Alkis F. BAIS Clare HEAVISIDE Christos ZEREFOS 《大气科学进展》2017,34(3):283-288
<正>1.Overview The 2016 Quadrennial Ozone Symposium(QOS-2016)was held on 4–9 September 2016 in Edinburgh,UK.The Symposium was organized by the International Ozone Commission(IO3C),the NERC Centre for EcologyHydrology and the University of Edinburgh,and was co-sponsored by the International Union of Geodesy and Geophysics,the International Association of Meteorology and Atmospheric 相似文献
10.
This study investigates how the choice of the planetary boundary layer (PBL) parameterization and dust emission scheme affects the prediction of dust entrainment simulated with a regional mesoscale model. For this analysis we consider a representative dust episode which occurred on April 2001 in the Aral Sea region. The meteorological fields were simulated using the PSU/NCAR MM5 modeling system considering two different boundary layer parameterizations. In each case, emitted dust fluxes were computed off-line by incorporating MM5 meteorological fields into the dust module DuMo. Several dust emission schemes with a prescribed erodible fraction and fixed threshold wind speed were the subject of our analysis. Implications to assessment of the anthropogenic fraction of dust emitted in the Aral region were investigated by conducting the full, half, and no lake modeling experiments.Our results show that the discrepancies in dust fluxes between the two different PBLs are much higher compared to the discrepancy associated with the use of considered dust production schemes. Furthermore, the choice of the PBL affects the timing and duration of a modeled dust event. We demonstrate that different combinations of the PBL parameterization and wind- or friction velocity-driven dust emission schemes can result in up to about a 50% difference in predicted dust mass caused by the Aral Sea desiccation. We found that the drying-up of the Aral cannot only affect the dust emission by expanding the source area, but also by affecting atmospheric characteristics, especially winds. These competitive factors add further complexity to quantification of the anthropogenic dust fraction in the region. 相似文献